My expertise is in the areas of regeneration, evolution, the nervous system and cell biology. I use a marine colonial tunicate, Botryllus schlosseri, characterized by having robust regenerative capabilities and an assayable and frequent (weekly) CNS (Central nervous system) tissue regeneration and loss throughout adult life. I believe that comparative studies on a simple chordate can help us elucidate the principal mechanisms that are the foundation of regeneration and aging.
I use a multidisciplinary methodology that integrates advanced single cell RNAseq, imaging, multi-parameter flow cytometric isolation of cellular populations and transplantation assays to elucidate the cellular and genetic changes associated with neuronal degeneration process in young and old colonies.
Yamanaka Factors in the Budding Tunicate Botryllus schlosseri Show a Shared Spatio-Temporal Expression Pattern in Chordates.
Frontiers in cell and developmental biology
2022; 10: 782722
In vertebrates, the four transcription factors Sox2, c-Myc, Pou5f1 and Klf4 are involved in the differentiation of several tissues during vertebrate embryogenesis; moreover, they are normally co-expressed in embryonic stem cells and play roles in pluripotency, self-renewal, and maintenance of the undifferentiated state in adult cells. The in vitro forced co-expression of these factors, named Yamanaka factors (YFs), induces pluripotency in human or mouse fibroblasts. Botryllus schlosseri is a colonial tunicate undergoing continuous stem cell-mediated asexual development, providing a valuable model system for the study of pluripotency in the closest living relatives of vertebrates. In this study, we identified B. schlosseri orthologs of human Sox2 and c-Myc genes, as well as the closest homologs of the vertebrate-specific Pou5f1 gene, through an in-depth evolutionary analysis of the YF gene families in tunicates and other deuterostomes. Then, we studied the expression of these genes during the asexual cycle of B. schlosseri using in situ hybridization in order to investigate their possible involvement in tissue differentiation and in pluripotency maintenance. Our results show a shared spatio-temporal expression pattern consistent with the reported functions of these genes in invertebrate and vertebrate embryogenesis. Moreover, Myc, SoxB1 and Pou3 were expressed in candidate stem cells residing in their niches, while Pou2 was found expressed exclusively in the immature previtellogenic oocytes, both in gonads and circulating in the colonial vascular system. Our data suggest that Myc, SoxB1 and Pou3 may be individually involved in the differentiation of the same territories seen in other chordates, and that, together, they may play a role in stemness even in this colonial ascidian.
View details for DOI 10.3389/fcell.2022.782722
View details for PubMedID 35342743
- Morphological Study and 3D Reconstruction of the Larva of the Ascidian Halocynthia roretzi JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022; 10 (1)
Sexual and asexual development: two distinct programs producing the same tunicate.
2021; 34 (4): 108681
Colonial tunicates are the only chordate that possess two distinct developmental pathways to produce an adult body: either sexually through embryogenesis or asexually through a stem cell-mediated renewal termed blastogenesis. Using the colonial tunicate Botryllus schlosseri, we combine transcriptomics and microscopy to build an atlas of the molecular and morphological signatures at each developmental stage for both pathways. The general molecular profiles of these processes are largely distinct. However, the relative timing of organogenesis and ordering of tissue-specific gene expression are conserved. By comparing the developmental pathways of B. schlosseri with other chordates, we identify hundreds of putative transcription factors with conserved temporal expression. Our findings demonstrate that convergent morphology need not imply convergent molecular mechanisms but that it showcases the importance that tissue-specific stem cells and transcription factors play in producing the same mature body through different pathways.
View details for DOI 10.1016/j.celrep.2020.108681
View details for PubMedID 33503429
Stem Cells and Innate Immunity in Aquatic Invertebrates: Bridging Two Seemingly Disparate Disciplines for New Discoveries in Biology.
Frontiers in immunology
2021; 12: 688106
The scopes related to the interplay between stem cells and the immune system are broad and range from the basic understanding of organism's physiology and ecology to translational studies, further contributing to (eco)toxicology, biotechnology, and medicine as well as regulatory and ethical aspects. Stem cells originate immune cells through hematopoiesis, and the interplay between the two cell types is required in processes like regeneration. In addition, stem and immune cell anomalies directly affect the organism's functions, its ability to cope with environmental changes and, indirectly, its role in ecosystem services. However, stem cells and immune cells continue to be considered parts of two branches of biological research with few interconnections between them. This review aims to bridge these two seemingly disparate disciplines towards much more integrative and transformative approaches with examples deriving mainly from aquatic invertebrates. We discuss the current understanding of cross-disciplinary collaborative and emerging issues, raising novel hypotheses and comments. We also discuss the problems and perspectives of the two disciplines and how to integrate their conceptual frameworks to address basic equations in biology in a new, innovative way.
View details for DOI 10.3389/fimmu.2021.688106
View details for PubMedID 34276677
- Sixty years of experimental studies on the blastogenesis of the colonial tunicate Botryllus schlosseri DEVELOPMENTAL BIOLOGY 2019; 448 (2): 293–308
A Notch-regulated proliferative stem cell zone in the developing spinal cord is an ancestral vertebrate trait
2019; 146 (1)
Vertebrates have evolved the most sophisticated nervous systems we know. These differ from the nervous systems of invertebrates in several ways, including the evolution of new cell types, and the emergence and elaboration of patterning mechanisms to organise cells in time and space. Vertebrates also generally have many more cells in their central nervous systems than invertebrates, and an increase in neural cell number may have contributed to the sophisticated anatomy of the brain and spinal cord. Here, we study how increased cell number evolved in the vertebrate central nervous system, investigating the regulation of cell proliferation in the lamprey spinal cord. Markers of proliferation show that a ventricular progenitor zone is found throughout the lamprey spinal cord. We show that inhibition of Notch signalling disrupts the maintenance of this zone. When Notch is blocked, progenitor cells differentiate precociously, the proliferative ventricular zone is lost and differentiation markers become expressed throughout the spinal cord. Comparison with other chordates suggests that the emergence of a persistent Notch-regulated proliferative progenitor zone was a crucial step for the evolution of vertebrate spinal cord complexity.
View details for DOI 10.1242/dev.166595
View details for Web of Science ID 000455850900002
View details for PubMedID 30552127
Differentiation and Induced Sensorial Alteration of the Coronal Organ in the Asexual Life of a Tunicate
OXFORD UNIV PRESS INC. 2018: 317–28
Tunicates, the sister group of vertebrates, possess a mechanoreceptor organ, the coronal organ, which is considered the best candidate to address the controversial issue of vertebrate hair cell evolution. The organ, located at the base of the oral siphon, controls the flow of seawater into the organism and can drive the "squirting" reaction, i.e., the rapid body muscle contraction used to eject dangerous particles during filtration. Coronal sensory cells are secondary mechanoreceptors and share morphological, developmental, and molecular traits with vertebrate hair cells. In the colonial tunicate Botryllus schlosseri, we described coronal organ differentiation during asexual development. Moreover, we showed that the ototoxic aminoglycoside gentamicin caused morphological and mechanosensorial impairment in coronal cells. Finally, fenofibrate had a strong protective effect on coronal sensory cells due to gentamicin-induced toxicity, as occurs in vertebrate hair cells. Our results reinforce the hypothesis of homology between vertebrate hair cells and tunicate coronal sensory cells.
View details for DOI 10.1093/icb/icy044
View details for Web of Science ID 000451994200013
View details for PubMedID 29873734
View details for PubMedCentralID PMC6104713
High-precision morphology: bifocal 4D-microscopy enables the comparison of detailed cell lineages of two chordate species separated for more than 525 million years
2015; 13: 113
Understanding the evolution of divergent developmental trajectories requires detailed comparisons of embryologies at appropriate levels. Cell lineages, the accurate visualization of cleavage patterns, tissue fate restrictions, and morphogenetic movements that occur during the development of individual embryos are currently available for few disparate animal taxa, encumbering evolutionarily meaningful comparisons. Tunicates, considered to be close relatives of vertebrates, are marine invertebrates whose fossil record dates back to 525 million years ago. Life-history strategies across this subphylum are radically different, and include biphasic ascidians with free swimming larvae and a sessile adult stage, and the holoplanktonic larvaceans. Despite considerable progress, notably on the molecular level, the exact extent of evolutionary conservation and innovation during embryology remain obscure.Here, using the innovative technique of bifocal 4D-microscopy, we demonstrate exactly which characteristics in the cell lineages of the ascidian Phallusia mammillata and the larvacean Oikopleura dioica were conserved and which were altered during evolution. Our accurate cell lineage trees in combination with detailed three-dimensional representations clearly identify conserved correspondence in relative cell position, cell identity, and fate restriction in several lines from all prospective larval tissues. At the same time, we precisely pinpoint differences observable at all levels of development. These differences comprise fate restrictions, tissue types, complex morphogenetic movement patterns, numerous cases of heterochronous acceleration in the larvacean embryo, and differences in bilateral symmetry.Our results demonstrate in extraordinary detail the multitude of developmental levels amenable to evolutionary innovation, including subtle changes in the timing of fate restrictions as well as dramatic alterations in complex morphogenetic movements. We anticipate that the precise spatial and temporal cell lineage data will moreover serve as a high-precision guide to devise experimental investigations of other levels, such as molecular interactions between cells or changes in gene expression underlying the documented structural evolutionary changes. Finally, the quantitative amount of digital high-precision morphological data will enable and necessitate software-based similarity assessments as the basis of homology hypotheses.
View details for DOI 10.1186/s12915-015-0218-1
View details for Web of Science ID 000367050800002
View details for PubMedID 26700477
View details for PubMedCentralID PMC4690324